Not just naive users either. I am very computer literate and yet I find myself in situations where I've skipped that text and only find it when I go back.
It makes me think when I'm designing things. If I have problems with stuff like that, how can I make it better.
Really, if people read everything they'd never get anything done. They see dozens to hundreds of things marked visually as important that they'll do fine ignoring, every single day. Of course they often miss the one or two per day that they actually needed to read.
Then there's the way styles are so different, especially on the web. Horribly user-hostile. How does this site mark something as important, assuming it bothers in the first place? Who knows. And if I'm only planning to be on it for 30s, I'm not going to learn that.
I guarantee you fewer than 50% of people who use a desktop computer at least once a week know how to multi-select and range-select using shift and ctrl on them, though. That's why you need the text—which many will, for reasons that are actually pretty good, ignore.
It is standard but it is not used often. In fact, I can’t remember the last time I saw one used that want some ancient, intranet application built on Cold Fusion.
Many users don’t even know you can use a key shortcut to copy/paste.
It makes me think when I'm designing things. If I have problems with stuff like that, how can I make it better.